What Eidos Said: ”Well, with a reinvention, it’s always gonna be a little different. And what people remember [varies from person to person].”
Also, in response to rumors of serious trouble behind the scenes:

“There have been some changes in personnel. The project’s been going on for a while. We were trying to get the DNA right – the essence of the game. It took a while because we tried a few things that just didn’t really fit. And hopefully, you’ll play it and see that we have a solid product. You know, rumors are rumors.”

My Experience: I am conflicted. As you can very obviously tell, the new Thief rubbed me the wrong way in quite a few places. AI and combat, especially, were well off the mark, and that’s definite cause for worry. Oh, and let’s not forget the linear, QTE-ridden escape scene, which felt completely at odds with pretty much everything ever – especially common sense, stealth (or even stealth-action), and the year 2013.

Thief’s level design, however, was solid, and I could see it meshing quite well with competent though basic systems and smart enemy placement if the AI gets stolen and replaced with pretty much anything else. No doubt about it, Thief needs some serious work, but I think there’s still potential. Deus Ex: Human Revolution was an absolute joy, and I can almost see the murky silhouette of a similar miracle skulking around in Thief’s gutters.

Also,there is still tons I wasn’t able to see. Other areas. More open slices of the world. Secrets (of which there will apparently be many). I’m also crossing my fingers for the story, which is still shrouded in a sooty smog of mystery.